Orographic Effects on Extreme Rainfall at Different Durations: A Case Study in Campania Region (Southern Italy)

Long-term probabilistic prediction of extreme rainfall at the regional scale isa significant tool in the mitigation of hydro-geological disasters: it actuallyprovides the starting point in the design of strategic hydraulic infrastructuresand emergency plans. A crucial task of regional estimation of extreme rainfallis how to include the complex effects of orographic barriers in a mathematicalmodel for Intensity-Duration-Frequency (IDF) curves. Here, an analysis ofhow orography can affect extreme rainfall at different durations is presentedfor three orographic systems that are very relevant for hydrological risk assessmentin the Campania Region in Southern Italy. Then, we introduce apower law model to link the amplification factor to the duration, thus allowinga simple and effective enhancement of the IDF model in mountainousareas.